Code 128 is a very effective, high-density symbology which permits the encoding of alphanumeric data. The symbology includes a checksum digit for verification, and the bar code may also be verified character-by-character verifying the parity of each data byte. This symbology has been widely implemented in many applications where a relatively large amount of data must be encoded in a relatively small amount of space. It's specific structure also allows numeric data to be encoded at, effectively, double-density.